Method (base)

1. Line a 8 x 8 inch baking dish / tin with grease-proof paper. Allow the paper to hang over the edges of the tin, this makes it easier for removing the bars when baked.
2. In a large bowl, combine the almond flour, oats, baking powder, maple / agave syrup and melted coconut. Mix well to combine.
3. Add 3/4 of the base mixture to the tin (save the other 1/4 for the crumble on top). Use your fingers to press down until you have a tightly packed, even layer. Set aside. The texture of the mixture should be squidgy. If it feels too dry, add in a splash more coconut oil / syrup. 

Method (blueberry filling)

1. Add the blueberries, lemon zest, lemon juice, sugar and cornstarch into a medium sized saucepan. Place the pan over medium heat, continuously stirring to prevent the blueberries from sticking and burning. Be careful lot to vigorously whisk or mash as you want the berries to retain their form.
2. Cook the berry mixture for approximately 3-5 minutes, or until thickened.
3. Pre-heat oven to 180 degrees c fan.
4. Pour the filling on top of the base layer. Use a spoon or spatula to make sure it’s even. You want this blueberry layer to be as flat as possible.
5. Sprinkle the remaining crumble on-top of the blueberries in an even layer, making sure the majority of the filling is covered.
6. Place in the middle of the oven and bake for 30 minutes. You’ll know they’re ready when the filling is bubbling and the crust is golden brown in colour.
7. Remove from the oven and allow to cool fully in the tin before lifting the slab out of the tin and cutting into squares with a sharp knife.
8. Serve and enjoy.